Fan enabling increased air volume

ABSTRACT

A fan enabling increased air volume includes at least a fan wheel and a driving unit for driving the fan wheel to maintain a uniform rotating speed. The fan wheel includes a hub and a plurality of blades radially extended from an outer periphery of the hub. The blades may be arranged on the hub in different manners, such as having a preceding blade overlapped a following blade, or having a blade root installation angle smaller than 53° and a blade tip inclination angle smaller than 46°, or having a solidity of blade roots larger than 1.5 and a solidity of blade tips larger than 1, so that the fan wheel produces increased air volume and accordingly enhanced cooling power at the uniform rotating speed.

This application is a Divisional of co-pending application Ser. No. 10/863,337, filed on Jun. 9, 2004, and for which priority is claimed under 35 U.S.C. § 120, the entire contents of all are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a fan enabling increased air volume, and more particularly to a fan with enhanced cooling power.

BACKGROUND OF THE INVENTION

With the increasing developments in technological fields, various kinds of electronic products are designed to provide more functions so as to increase their value in use. The increased functions necessitate the provision of more components or parts in a system having a fixed volume. The large quantity of components or parts in the electronic product result in reduced internal spaces of the system while produce more heat in the limited internal spaces of the system to necessitate the use of cooling means to carry away the produced high amount of heat. A cooling fan is most frequently selected to solve the problem of heat produced in the system because it produces convective airflows to carry away the produced heat from the system. However, when the airflows produced by the cooling fan inward flow through the system, they are inevitably impeded by the components or parts densely arranged in the system to result in largely reduced cooling effect. Therefore, it is necessary to increase the air volume and air pressure produced by the cooling fan to maintain the expected cooling effect. Currently, there are two ways to achieve this purpose. The first way is to increase the rotating speed of the motor of the fan, and the second way is to change the blade structure of the fan. However, the increased motor rotating speed would result in consumption of more power and accordingly waste of more energy.

FIG. 1 is a graph showing different fan characteristic curves for a general fan used with a system having a relatively small number of components or parts arranged therein. When the fan is started to operate, airflows produced by the fan are interfered in their flow paths by the components in the system. That is, the impedance of the internal components of the system will prevent the airflows produced by the fan from flowing smoothly to result in loss of air pressure. In the graph of FIG. 1, the curve A1 is a system impedance curve representing changes in the loss of air volume produced by the fan, and will become lowered when the number of components or parts in the system is low; the curve T is an air volume curve representing the operating characteristic of the fan measured in an air tunnel; the point P is an intersection of the curve A1 with the curve T representing an operating point of the system; and the circled area A surrounding the point P is an operating range representing the operating performance of the fan used with the system having lower number of internal components.

Please refer to FIG. 2 that is a graph showing different fan characteristic curves for a fan having overlapped blades and operating at non-uniform rotating speeds for effectively solving the problem of produced heat in a system having highly densely arranged internal components or parts. When the overlapped blades of the fan are rotated to produce airflows, the airflows are interfered in their flow paths by the components in the system. That is, the impedance of the internal components of the system will prevent the airflows produced by the overlapped blades of the fan from flowing smoothly to result in loss of air pressure. In the graph of FIG. 2, the curve B1 is a system impedance curve representing changes in the loss of air volume produced by the fan, and will become higher when the number of components or parts in the system is high; the curve T1 is an air volume curve representing the operating characteristic of the fan with overlapped blades measured in an air tunnel; the point P1 is an intersection of the curve B1 with the curve T1 representing an operating point of the system; and the circled area Q surrounding the point P1 is an operating range representing the operating performance of the fan with overlapped blades operated at non-uniform rotating speeds to carry away the heat produced in the system.

In the graph shown in FIG. 3, the curve T3 represents an air volume curve for a fan having a motor with increased number of coils in an attempt to upgrade the fan performance; and point P2 is an intersection of the curve T3 with the system impedance curve B1 representing an operating point of the system. The operating point P2 is obviously much higher than the operating point P1 at the intersection of the curve T1 with the system impedance curve B1. That is, the whole curve T3 is higher than the curve T1 and represents the fan with motor having increased number of coils provides increased air volume. However, the motor with increased number of coil would largely increase the power consumption thereof and tends to overheat and burn out due to increased rotating speed.

It is therefore tried by the inventor to develop a fan enabling increased air volume that increases air pressure and volume without the need of increasing the power for drive the fan.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a fan wheel having a plurality of blades that may be differently arranged on a hub, so that the blades either overlap one another, or have a blade root installation angle smaller than 53° and a blade tip inclination angle smaller than 46°, or have a solidity of blade roots larger than 1.5 and a solidity of blade tips larger than 1, so that the fan wheel is able to produce increased air volume and enhanced cooling efficiency at a uniform rotating speed.

Another object of the present invention is to provide a fan wheel that operates at a uniform rotating speed to save power consumption needed to drive the fan wheel.

To achieve the above and other objects, the fan enabling increased air volume according to the present invention includes at least a fan wheel and a driving unit for driving the fan wheel to maintain a uniform rotating speed. The fan wheel includes a hub and a plurality of blades radially extended from an outer periphery of the hub.

In a first embodiment of the present invention, the blades are arranged on the hub with a preceding blade overlapping a following blade. In a second embodiment of the present invention, the blades are arranged on the hub with a blade root installation angle smaller than 53° and a blade tip inclination angle smaller than 46°. In a third embodiment of the present invention, the blades are arranged on the hub with a solidity of blade roots larger than 1.5 and a solidity of blade tips larger than 1. In either case, the fan wheel is able to produce increased air volume and accordingly enhanced cooling power at the uniform rotating speed.

Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the following detailed description and the accompanying drawings, which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1 is a graph showing fan characteristic curves for a conventional fan used with a system having a relatively small number of components or parts arranged therein;

FIG. 2 is a graph showing fan characteristic curves for a conventional fan with overlapped blades and used with a system having a relatively large number of components or parts arranged therein;

FIG. 3 is a graph comparing a fan characteristic curve for a conventional fan having a motor with increased number of coils with the fan characteristic curves shown in FIG. 2;

FIG. 4 is an exploded sectional view of a fan according to a first preferred embodiment of the present invention;

FIG. 5 is an assembled sectional view of FIG. 4;

FIG. 6 is a top plan view of the fan according to the first preferred embodiment of the present invention;

FIG. 7 is a graph showing a rotating speed deviation curve for a fan having a uniform rotating speed according to the first preferred embodiment of the present invention;

FIG. 8 is a graph comparing an air volume curve for the uniform-speed fan according to the first preferred embodiment of the present invention to fan characteristic curves for a conventional fan having non-uniform rotating speeds and used with a system having densely arranged internal components;

FIG. 9 is a top plan view of another fan according to the first preferred embodiment of the present invention with blades thereof overlapped in a second manner;

FIG. 10 is a top plan view of a further fan according to the first preferred embodiment of the present invention with blades thereof overlapped in a third manner;

FIG. 11 is a stretch-out sectional view showing blade roots for a fan according to a second preferred embodiment of the present invention;

FIG. 12 is a stretch-out view showing blade tips for the fan according to the second preferred embodiment of the present invention;

FIG. 13 shows a stretch-out view of a hub and sectioned side view of blade roots for a fan according to a third preferred embodiment of the present invention;

FIG. 14 shows the solidity of blade roots for the fan according to the third preferred embodiment of the present invention;

FIG. 15 shows a stretch-out view of a hub and sectioned side view of blade tips for the fan according to the third preferred embodiment of the present invention; and

FIG. 16 shows the solidity of blade tips for the fan according to the third preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIGS. 4, 5, and 6, in which a fan enabling increased air volume according to a first preferred embodiment of the present invention is shown. As shown, the fan of the present invention includes at least a housing 21, a fan wheel 22, and a driving unit 23. The fan wheel 22 includes a hub 221 and a plurality of overlapped blades 222 that radially outward extend from an outer periphery of the hub 221. Each of the blades 222 includes a blade root 2221 directly connected with the hub 221, a blade body 2222 extended from the blade root 2221 and having a first blade edge 2223 and a second blade edge 2224, and a blade tip 2225 located at an outer end of the blade body 2222. The blades 222 overlap one another in such a manner that the blade root 2221 and an area including an upper part of the blade body 2222 and the first blade edge 2223 of a preceding blade 222 overlaps the blade root 2221 and an area including a lower part of the blade body 2222 and the second blade edge 2224 of a following blade 222. The hub 221 includes a spindle 2211 having a neck portion 22111 formed thereon for a retaining ring 26 to engage therewith. The housing 21 includes a hub seat 211 with a hollow bushing 212 provided thereon for a bearing 25 to mount therein. The driving unit 23 includes a driving circuit board 231, a stator 232, and a rotor 233.

To assemble the fan of the present invention, first firmly fix the rotor 233 in the hub 221 of the fan wheel 22, and then sequentially position the retaining ring 26 and the bearing 25 in the bushing 212, and then put the driving circuit board 231 and the stator 232 around the bushing 212. Thereafter, extend the spindle 2211 of the fan wheel 22 through the bearing 25 with the retaining ring 26 engaged with the neck portion 22111 of the spindle 2211, so that the spindle 2211 is rotatably connected to the bushing 212 without the risk of separating from the bushing 212. Finally, connect the driving circuit board 231 to the stator 232, which is magnetically connected to the rotor 233, so that the stator 232 and the rotor 233 are excited when the driving circuit board 231 produces currents. In this manner, the fan wheel 22 could rotate at a uniform speed as soon as it is started, and produces airflows.

Please refer to FIGS. 4 and 7 at the same time. The fan with overlapped blades and operated at a uniform rotating speed, as described with reference to FIGS. 4, 5, and 6, has a rotating speed deviation curve F1 for a rotating speed preset for the fan. When the curve F1, under the preset fixed rotating speed, indicates a deviation within a range of ±8%, the air volume produced by the fan increases gradually. That is, when the fan with overlapped blades has a uniform rotating speed and a rotating speed deviation of the fan between a starting speed and an end speed is limited to a range of ±8%, the air volume produced by the fan increases. And, when the rotating speed deviation between the starting speed and the end speed is limited to 0%, the fan with overlapped blades having a uniform rotating speed actually has a fixed rotating speed, which allows the fan to produce further increased air volume. The fan of FIG. 4 has an air volume curve T2 as shown in FIG. 8. That is, the curve T2 is obtained when the fan with overlapped blades 222 according to the first preferred embodiment of the present invention rotates at a uniform speed. The curve T2 intersects with the system impedance curve B1 at a point that is a system operating point P2. As can be seen from FIG. 8, the operating point P2 of the fan with overlapped blades and uniform rotating speed has a position in the operating area Q the same as the position of the operating point P2 at the intersection of the air volume curve T3 of the fan with motor having increased number of coil with the system impedance curve B1, and is obviously higher than the operating point P1 of the general fan with overlapped blades and non-uniform rotating speed. That is, the air pressure and air volume corresponding to the operating point P2 are obviously higher than that corresponding to the operating point P1. In other words, the whole air volume curve T2 indicates the fan of the present invention having overlapped blades and uniform rotating speed has an optimal operating performance to provide largely increased air pressure and effective cooling of a system with densely arranged internal components or parts. The fan of the present invention eliminates the drawbacks existed in the conventional fan with motor having increased number of coils, such as increased power consumption and easy burnout of motor due to high rotating speed thereof, while upgrades the fan performance to produce increased air pressure and air volume without increasing the power needed by the motor.

FIGS. 9 and 10 shows two fans according to the first preferred embodiment of the present invention but have a plurality of blades 222 overlapped one another in different manners. In FIG. 9, the blades 222 overlaps one another in such a manner that the blade root 2221 of a preceding blade 222 overlaps the blade root 2221 of the following blade 222. In FIG. 10, the blades 222 overlaps one another in such a manner that the blade body 2222 of a preceding blade 222 overlaps the blade body 2222 of the following blade 222. In either case, the fan of the present invention provides an optimal performance to produce increased air pressure and enhanced cooling efficiency without increasing the power consumption thereof.

Please refer to FIGS. 11 and 12 that are spread-out views of a fan wheel 32 for a fan according to a second preferred embodiment of the present invention to show a sectioned side view of blade roots 3221 and a side view of blade tips 3225, respectively, of the blades 322 on the fan wheel 32. The fan wheel 32 is structurally and functionally similar to the fan wheel 22 in the first preferred embodiment, except that the blades 322 on the fan wheel 32 do not overlap one another, and the blade root 3221 connected with the hub 321 has an inclination equal to an angle contained between a blade chord C3 at the blade root 3221 and a horizontal line. That is, the blade root 3221 has an installation angle θ1 smaller than 53°. Moreover, the blade tip 3225 of the blade 322 on the hub 321 has an inclination equal to an angle contained between a blade chord C4 at the blade tip 3225 and a horizontal line. That is, the blade tip 3225 has an inclination angle θ2 smaller than 46°. With these arrangements, the fan according to the second preferred embodiment of the present invention rotating at a uniform speed can produce increased air pressure and air volume to achieve an optimal performance and increased cooling efficiency without increasing the power consumption thereof.

FIGS. 13 to 16 are spread-out views of a fan wheel 42 for a fan according to a third preferred embodiment of the present invention, wherein FIGS. 13 and 14 are sectioned side views of blade roots 4221, and FIGS. 15 and 16 are side views of blade tips 4225 of the blades 422 on the fan wheel 42. The fan wheel 42 is structurally and functionally similar to the fan wheel 22 in the first preferred embodiment, except that the blades 422 on the fan wheel 42 do not overlap one another, and a solidity of blade roots of the blades 422 connected to the hub 421 is larger than 1.5. That is, C1÷S1>1.5, where C1 is referred to as a blade chord at the blade root and represents a linear distance from an upper end 42211 a to a lower end 42212 a of a blade root 4221 a of a blade 422 a, and S1 is a linear distance from the upper end 42211 a of the blade root 4221 a of a blade 422 a to the upper end 42211 b of the blade root 4221 b of an adjacent blade 422 b, or a linear distance from the lower end 42212 a of the blade root 4221 a of a blade 422 a to the lower end 42212 b of the blade root 4221 b of an adjacent blade 422 b (see FIGS. 13 and 14). Moreover, a solidity of blade tips of the blades 422 is larger than 1. That is, C2÷S2>1, where C2 is referred to as a blade chord at the blade tip and represents a linear distance from an upper end 42251 a to a lower end 42252 a of a blade tip 4225 a of a blade 422 a, and S1 is a linear distance from the upper end 42251 a of the blade tip 4225 a of a blade 422 a to the upper end 42251 b of the blade tip 4225 b of an adjacent blade 422 b, or a linear distance from the lower end 42252 a of the blade tip 4225 a of a blade 422 a to the lower end 42252 b of the blade tip 4225 b of an adjacent blade 422 b (see FIGS. 15 and 16). With the above arrangements, including the non-overlapped blades, a solidity of blade roots larger than 1.5 and a solidity of blade tips larger than 1, and a uniform rotating speed, the fan according to the third preferred embodiment of the present invention can produce increased air pressure and air volume to achieve an optimal performance and increased cooling efficiency without increasing the power consumption thereof.

The invention being thus described, it it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims. 

1. A fan enabling increased air volume, comprising: a fan wheel, and a driving unit for driving said fan wheel to maintain a uniform rotating speed; wherein said fan wheel includes: a hub, and a plurality of blades radially extended from an outer periphery of said hub, said plurality of blades having a solidity of blade roots larger than 1.5, and a solidity of blade tips larger than 1, whereby said fan wheel produces increased air volume and enhances cooling power at said uniform rotating speed.
 2. The fan enabling increased air volume as claimed in claim 1, wherein said driving unit includes a driving circuit board.
 3. The fan enabling increased air volume as claimed in claim 1, further comprising a housing in which said fan wheel and said driving unit are mounted.
 4. The fan enabling increased air volume as claimed in claim 1, wherein said uniform rotating speed of said fan wheel has a deviation within a range of ±8%. 